iOS zoom problem

[imaumac]

Hi.
i have some pictures with scrollview, and you can zoom in to top, but then you can not zoom out, here is the project ( link below ).

Please, if some body download , could you tellme why i can not zoom out, (or general problem with zoom)
please really need help.

here is the project.

http://www.1572-8.com/aaaa-iPhone-Dev-folder/zz-project-xcode/ZOOMPRUEBA2.zip

 

[imaumac]

please help !
i need to know how reset zoom to 1:1 when press a button please.